1. Field of the Invention
The present invention relates to apparatus for sensing the position of a center pivot irrigation system in a field, and more particularly pertains to a new system for determining the position of the rotatable arm of a center pivot irrigation system using data from a Global Positioning Satellite (GPS), which may be used in controlling various aspects of the function of the center pivot irrigation system using a network-based system interface.
2. Description of the Prior Art
Irrigation systems have been employed for years to distribute water to areas of land on which a crop is growing. One type of irrigation system, the so-called “center pivot” system, employs a central tower about which a rotatable arm pivots, or rotates, at an elevated position above the ground. A conduit extends along this rotatable arm and radiates outwardly from the center tower, and water is sprayed or otherwise distributed from the conduit at points along the conduit. The rotatable arm includes one or more towers to maintain the conduit in the elevated position above the ground, and each of the towers is typically supported by one or more wheels that rotate while the rotatable arm is pivoted about the center tower. The radially-outermost tower is typically called the end tower, and the end tower may include an “end gun” that sprays water radially outward from the end tower of the rotatable arm.
A number of operational aspects of the center pivot may be controlled, including the starting and the stopping points for the rotatable arm as well as the “on” and “off” points for the end gun, which may be turned off while the rest of the center pivot system continues to distribute water (such as when the end gun would spray water on a road adjoining the field). Conventionally these aspects are controlled in the field by a controller that is positioned in the field and programmed in the field. The operation of the various aspects of the center pivot irrigation system is then keyed upon the angular position of the rotatable arm, which is often determined by a sensor at the center tower that detects the movement or the angular position of the rotatable arm relative to a reference angular position, such as a northward extending position. Thus, as the rotatable arm pivots and the angular position of the rotatable arm changes, various operational aspects of the center pivot irrigation system may be initiated, adjusted, or terminated.
Recently, there have been attempts to use Global Positioning System (GPS) technology to determine the orientation of the rotatable arm, using one, two, three or more GPS antenna/receiver units. However, the systems tend to be relatively complex, particularly since the known GPS-based systems still rely upon the technique of determining the angular orientation of the rotatable arm for controlling the center pivot irrigation system. For example, the system described in U.S. Pat. No. 6,928,339 to Barker requires the user to determine the coordinates of the location of the center pivot in the field, program the coordinates of the center pivot location into the control system in the field, and then the system continuously calculates and recalculates the azimuth or angular orientation of the rotatable arm using the coordinates of the center pivot location and the coordinates supplied by a GPS receiver unit mounted on one of the towers, and then compares the current azimuth with the azimuths associated with various actions for the irrigation system in an operational program stored on the irrigation system. This approach is believed to be unnecessarily complex for this purpose, and does not readily lend itself to remotely monitoring of the angular orientation of the rotatable arm, or to remotely controlling the operation of the various aspects of the center pivot irrigation system.
Further, most if not all known systems utilize monitoring and programming operations that are performed in the field, or at least must be changed in the field, and this factor makes the operation of the system more difficult, or at least inconvenient, for the operator of the system, especially for operators that are responsible for monitoring and controlling multiple center pivot irrigation systems.
It is therefore believed that there is a need for a position sensing and controlling system for center pivot irrigation system that facilitates remote monitoring and controlling of a center pivot irrigation system that is not unnecessarily complex in design.